[PATCH] usb: gadget: renesas: add support for RZ/G2L SoC

[Marek Vasut]

On 4/16/26 4:14 PM, Michele Bisogno wrote:

Hello Michele,

> Thank you for the review and the link to the Linux implementation.
> 
>> Regulator change should be a separate patch please.
> 
> I agree. I will split the regulator changes into a separate patch
> for the v2 series to keep the subsystem changes distinct.
> 
>> drivers/usb/gadget/rcar is pulled from Linux 1b4861e32e46...
>> but none of these changes in this patch are even in Linux next.
> 
> The RZ/G2L support in Linux relies heavily on DMA for data transfers.
> In U-Boot, we are primarily using the PIO path. The refactoring
> in fifo.c (switching to ioread8/iowrite8) was found to be necessary
> to handle trailing bytes and alignment specifically for the RZ/G2L
> bus when DMA is not active.

If Linux also contains the PIO code, it would also benefit from matching 
improvement, right ?

> Additionally, the usb_del_gadget_udc() change in common.c addresses
> a re-entrancy bug unique to U-Boot's gadget lifecycle. Without
> this, the UDC list becomes stale, causing the board to crash if
> a command like 'ums' is executed more than once.

This should be a separate bugfix patch.

>> The addition of RZ/G2L into USBHS driver in Linux was much simpler
> 
> I agree that moving the RZ/G2L specifics in common.c to a platform
> dependent file (similar to Linux) would be the cleaner long-term
> architecture. However, doing so would require a much more invasive
> refactoring of the existing driver structure. I opted for these
> minimal changes to maintain stability for existing R-Car Gen3
> users while enabling RZ/G2L support.
> 
> I will prepare a v2 series with the patches split as requested.

Ideally, let's try to keep the Linux and U-Boot driver code base 
synchronized as much as possible.

Thank you !